The firm last month agreed to a settlement with the Conservation Law Foundation
, a statewide environmental group that had appealed a state permit for the plant, alleging the gas-burning plant would not meet the state’s strict law to reduce greenhouse gases.

As part of the settlement, Footprint agreed to further reduce carbon dioxide emissions by 2050, when the plant also would be closed.

The filing asserts that the new plant would violate the federal Clean Air Act.

Footprint plans to close Salem Harbor on May 31, but the new appeal could delay the demolition schedule, according to the company.

“The latest appeal could slow the demolition progress, delaying the positive impact the new plant will have on the city and the environment,” Footprint said in a statement to the Globe.

Footprint’s new facility would run on the latest power plant technology. It will have about 30 employees, Footprint’s top leader said.

“Some of the jobs will be similar to what’s here now,” Peter Furniss, chief executive officer of Footprint, said in an interview at the plant.

He cited positions such as watch engineers or a plant operator. “But we’re really working with different technology. If a major problem comes up, you call [General Electric] and say, ‘What’s your monitor saying?’ ”

Most of Salem Harbor’s 105 workers will be laid off on May 31. But a handful will be kept on to wind down operations, and some employees could stay on during construction of the new plant, Furniss said.

“We will need a core group here, and hopefully they will be from the existing plant. But we haven’t fully fleshed that out yet,” he said.

Separately, Footprint made $500,000 available to help workers train for new jobs. “We wanted people to be able to start on whatever training they would need to help them get to the next step of a career,” Furniss said.

Some workers already have started to retrain as truck drivers, fuel burner technicians, or in the heating, ventilation, and air conditioning field.

“They were pretty much open to helping you retrain for whatever you wanted to pursue,” said Beth Tobin, the plant’s stockroom manager, who has worked at Salem Harbor for 28 years.

“But I would tell you, I think everyone wishes we could come back to work at the new plant if they could. But we also realize this is a whole new industry. It will be all high-tech.”